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intermitent bog down

 
Old 03-31-2013, 12:02 PM
  #1  
kjvette92
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Default intermitent bog down

I have a 92 LT1, I have had this problem 3 times where I am just accelerating and my engine just sputters and bogs down, till it stalls and it will start right back up and sputter some more; then it will just start running fine again. I feel like it's a fuel pump problem or a computer problem. I will drive it for a month and never have it happen again and then it starts......any idea's??????
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Old 03-31-2013, 06:50 PM
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leesvet
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dirty socks.


Yessir,

ya got dirty socks.





If it were acting up each day, or even each week I;d say fluffy was dead or dying. The consistancy of a problem is often the best clue as to what it is. A cat will plug and seem to be worse when its very hot or maybe not hot at all. Plugged cats are not studied a whole lot, not a lot of grant money goes there for reaearch so I'd say each situation is different but what they ALL have in common,. once fluffy gets plugged...fluffys gonna die.
Plugged cats cause slow revving, the need to push the pedal more to maintain speed or uphills, less response. Sluggish. It gets worse each day until the engine cannot generate enough power to get past 30 mph. Gutless.

Bad fuel filter usually causes poor performance, sputtering, backfiring and misfiring. Gutless performance. Weak. Once the filter is plugged...it stays plugged and gets worse till it cannot let ANY fuel pass..so the engine dies. Might start again but it will not rev.

Many sensors could cause a similar problem,..sluggish running, weakness with occasional misfiring..BUT, when a sensor fails there should be a DTC (code) set and stored in memory with the SES alert to notify the driver. Too many to go thru here, but you CAN order a set of FSM's for your reading pleasure. Good for maint and diagnostics as well.
$75 used, slightly more new. Used are prefered due to better color in the electrical drawings..
Plus used sometimes have some useful notes.


This could be a momentary break in the power supply. Bad cables act like this and behave as described. The HEI takes a good amount of battery, so when its down or low...it pukes out and acts like the key was turned off as you coast down. Gets a good contact again and its running like new...till next time. No codes or ECM help with this one.
Out of all, the most likely suspect is your sock.

Dirty socks.

This will cause an intermittent starvation for fuel, then some gets thru, then may not happen again for days. The sock will refill with fuel as soon as the pump stops trying to pull some thru, or as fast as you can turn it off. This lets the fuel seep back in the sock and to the pump. Might run ok for a week...month maybe. It don't last though.. The longer you drive it like this the more frequent the "downtime" will become until its daily. When you park at nite the fuel backwashes out of the sock taking some trash with it. This allows fuel to flow back IN thru the sock for a while so it does not appear to be blocked.. It'll mess with ya a little bit.. but its easy to deal with once understood.

Fuel pressure test should show you a steady needle on the test gauge, to indicate there is smooth steady flow thru the sock. An erratic needle tells you there is something causing the flow to be irregular up to that point and the ONLY 3 things that can possibly be are the pump itself, your sock and/or the fuel filter. The pressure regulator could cause a problem ..but those usually die and stay dead...and leak everywhere. The signs are too obvious.

short answer

IMO:

fuel strainer/sock. In-tank, on the pump. $5 at finer auto parts retailers everywhere.
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Old 04-01-2013, 07:18 PM
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93Rubie
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Originally Posted by kjvette92 View Post
I have a 92 LT1, I have had this problem 3 times where I am just accelerating and my engine just sputters and bogs down, till it stalls and it will start right back up and sputter some more; then it will just start running fine again. I feel like it's a fuel pump problem or a computer problem. I will drive it for a month and never have it happen again and then it starts......any idea's??????
How low is your fuel level when this happens?
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Old 04-02-2013, 06:33 AM
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On 2 of the times I was down to 1/4 tank. however the last time I had at least a half tank but was going up a very steep hill. I had the computer scanned....no error, I'm almost certain it;s fuel filter or the dirty socks.
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Old 04-02-2013, 10:01 AM
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leesvet
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Actually the 2 go together...

running low on fuel (below 1/4) will send more trash to the sock where it gets sucked in. With low fuel there is also less pressure outside the sock to help 'feed' fuel into the sock.

At ANYTIME if the sock becomes exposed the pump will instantly loose its "bite" on the fuel and pressure will fall off for a second...or more. During this time the engine will react and stop producing power. I just did this dance yesterday diagnosing a bad regulator...on my car the instant that pressure falls below 32-34..the engine misbehaves and falls off. If it drops below 30psi ...it misfires severly and stalls.

So, the brief time the sock is exposed to air IS enough to cause a stall.
You should have a baffle in the tank but....its a POS that breaks loose and just does not work after a while.
We have a thread on how to build a new system to make sure the pump stays submerged in fuel no matter how low the tank is.
If you are interested I will find it and post a copy. Others have used this with good results.
At this point, its best to go ahead and change the pump and sock while you are in the tank. The fuel cools the pump, so if it was low enough to cause a stall or power loss it was too low to keep the pump cool. Its been damaged and WILL fail at some point.
On the filter, remember if the filter was dirty, all that debris had to pass thru the pump & sock to get there

Dirty socks.
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Old 04-02-2013, 10:27 AM
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Originally Posted by 93Rubie View Post
How low is your fuel level when this happens?
Try it with a full tank. When I was running the stock tank my car would bog at the track if I was anywhere near a half tank.
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Old 04-02-2013, 02:59 PM
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Filling the tank has corrected the problem....I'm sure you guys are right on the money with the sock and baffle being the culprit.
I would like the link on how to correct this problem to ensure the pump stay submerged....until then I guess I need to make sure my tank stays 3/4 or better.
I am grateful for the responses; want to get it right now that it might get warmer.
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Old 04-24-2013, 08:00 AM
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Originally Posted by kjvette92 View Post
Filling the tank has corrected the problem....I'm sure you guys are right on the money with the sock and baffle being the culprit.
I would like the link on how to correct this problem to ensure the pump stay submerged....until then I guess I need to make sure my tank stays 3/4 or better.
I am grateful for the responses; want to get it right now that it might get warmer.
I ended up replacing the fuel pump, baffle was good, I also replaced the sock. Car is running like a champ.....no more issues.
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Old 06-10-2019, 08:21 AM
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Eddie Scholl
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Originally Posted by leesvet View Post
dirty socks.


Yessir,

ya got dirty socks.





If it were acting up each day, or even each week I;d say fluffy was dead or dying. The consistancy of a problem is often the best clue as to what it is. A cat will plug and seem to be worse when its very hot or maybe not hot at all. Plugged cats are not studied a whole lot, not a lot of grant money goes there for reaearch so I'd say each situation is different but what they ALL have in common,. once fluffy gets plugged...fluffys gonna die.
Plugged cats cause slow revving, the need to push the pedal more to maintain speed or uphills, less response. Sluggish. It gets worse each day until the engine cannot generate enough power to get past 30 mph. Gutless.

Bad fuel filter usually causes poor performance, sputtering, backfiring and misfiring. Gutless performance. Weak. Once the filter is plugged...it stays plugged and gets worse till it cannot let ANY fuel pass..so the engine dies. Might start again but it will not rev.

Many sensors could cause a similar problem,..sluggish running, weakness with occasional misfiring..BUT, when a sensor fails there should be a DTC (code) set and stored in memory with the SES alert to notify the driver. Too many to go thru here, but you CAN order a set of FSM's for your reading pleasure. Good for maint and diagnostics as well.
$75 used, slightly more new. Used are prefered due to better color in the electrical drawings..
Plus used sometimes have some useful notes.


This could be a momentary break in the power supply. Bad cables act like this and behave as described. The HEI takes a good amount of battery, so when its down or low...it pukes out and acts like the key was turned off as you coast down. Gets a good contact again and its running like new...till next time. No codes or ECM help with this one.
Out of all, the most likely suspect is your sock.

Dirty socks.

This will cause an intermittent starvation for fuel, then some gets thru, then may not happen again for days. The sock will refill with fuel as soon as the pump stops trying to pull some thru, or as fast as you can turn it off. This lets the fuel seep back in the sock and to the pump. Might run ok for a week...month maybe. It don't last though.. The longer you drive it like this the more frequent the "downtime" will become until its daily. When you park at nite the fuel backwashes out of the sock taking some trash with it. This allows fuel to flow back IN thru the sock for a while so it does not appear to be blocked.. It'll mess with ya a little bit.. but its easy to deal with once understood.

Fuel pressure test should show you a steady needle on the test gauge, to indicate there is smooth steady flow thru the sock. An erratic needle tells you there is something causing the flow to be irregular up to that point and the ONLY 3 things that can possibly be are the pump itself, your sock and/or the fuel filter. The pressure regulator could cause a problem ..but those usually die and stay dead...and leak everywhere. The signs are too obvious.

short answer

IMO:

fuel strainer/sock. In-tank, on the pump. $5 at finer auto parts retailers everywhere.
Im sorry the whole time i was reading this i thought you where just trolling us with saying our socks are bad lol... then i realized your talking about the fuel strainer lol.
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